Chair back



FIG. 1 is a left side, front and top perspective view of a chair back,showing our new design.

FIG. 2 is a front elevational view thereof;

FIG. 3 is a top plan view thereof, the bottom plan view being amirror-image thereof; and,

FIG. 4 is a right side elevational view thereof, the left sideelevational view being a mirror-image thereof.

The broken lines are for illustrative purposes only and form no part ofthe claimed design.

CLAIM The ornamental design for a chair back, as shown and described.